All of radiotherapy devices are designed to be checked regular intervals whether a precise radiation dose reaches a target point by taking into consideration stability and reappearance. Today, when a radiation beam is measured using such a radiotherapy device, a water phantom and a solid water-equivalent phantom are chiefly used with the recommendation of International Atomic Energy Agency (IAEA).
In general, the measurement of radiation is performed for quality assurance (QA) of the measurement of radiation by taking into consideration the volume of a radiotherapy patient and the location of a tumor. The number of beams radiated is many and has many angles. However, such conventional equipment has a difficulty in accurate measurement in the recent scheme that requires precision and complexity. More specifically, if a non-uniformity medium, such as air or a bone, is included in an object whose radiation will measured, corresponding copying is difficult and it is also difficult to insert a measurement unit. In order to implement a non-uniformity medium, a specially produced phantom is used in some organs, but there is a problem in that even an opportunity cost given up due to the use of the specially produced phantom is included in addition to a cost.
Today, a phantom used in a radiotherapy-related task site needs to be fabricated according to a single measurement target and to be used for only such a purpose. That is, it is difficult to use a conventional single phantom for various purposes for measurement targets which have different various media and have different densities even in portions within one medium.